Adsorption of cetyltrimethyl ammonium bromide (CTAB) surfactant to organophilization of palygorskite clay
adsorption, palygorskite, organophilic clay, organophilization
The petroleum industry accounts for a significant portion of the clay market share, where they are used in drilling fluids as thixotropic agents. It is responsible for some important physicochemical characteristics, which must be controlled so that the fluid can perform its functions properly. Among the important functions of clays in drilling are cooling the bit, waterproofing the geological formation and maintaining solid suspension. In water-sensitive drilling operations, the use of oil-based fluid is often necessary, and in this case, clays lose their thixotropic properties, since their natural state is hydrophilic, they cannot be used without undergoing an organic treatment to make them hydrophobic. Different studies have been carried out in order to obtain organophilic clays, by different methods, capable of meeting the necessary requirements for their use. In this context, this research aimed to determine the ideal content (maximum point of surfactant adsorption) of palygorskite (Plg) to obtain organophilization using cationic surfactant cetyltrimethyl ammonium bromide (CTAB) at different concentrations. The adsorption tests were carried out in a finite bath, varying the content of Plg and CTAB in the solution. In these tests, parameters such as time, temperature, pH and thermodynamic characteristics were observed. To analyze the results, mathematical models for adsorption processes (Langmuir, Freundlich, Dubinin-Radushkevitch (D-R) and Tempkin) were used. The collected data showed that an increase in clay content in the dispersion leads to a decrease in surfactant adsorption on clay. However, it was possible to obtain the ideal clay content for the organophilization of Plg at different concentrations of the CTAB surfactant. The data obtained in the experiments fit well with the Freundlich model. The Dubinin-Radushkevitch and Tempkin isotherms confirmed the chemical adsorption of CTAB on clay Plg.